A wireless device (e.g., a cellular phone or a smartphone) in a wireless communication system may transmit and receive data for two-way communication. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a radio frequency (RF) carrier signal with data to generate a modulated RF signal, amplify the modulated RF signal to generate a transmit RF signal having the proper output power level, and transmit the transmit RF signal via an antenna to another device such as, for example, a base station. For data reception, the receiver may obtain a received RF signal via the antenna and may amplify and process the received RF signal to recover data sent by the other device.
Amplification of RF signals may be provided by one or more amplifiers. In some exemplary embodiments, the amplified RF signal may include one or more undesired frequency bands. For example, an amplified oscillator signal may include one or more harmonic signals that may interfere with and/or impede functionality of circuits included within the transmitter and/or the receiver of the wireless device. Therefore, filtering the amplified oscillator signal to suppress and/or attenuate the undesired frequency bands may improve performance of the wireless device.
Thus, there is a need to control the amplification of RF signals and attenuate one or more frequency bands that may be included with the amplified RF signals.